Problem: $\dfrac{1}{100} + \dfrac{3}{10} = {?}$
Solution: The fractions must have the same denominator before you can add them. Rewrite $\dfrac{3}{10}$ as $\dfrac{30}{100}$ $\dfrac{1}{100} + \dfrac{30}{100} = {?}$ $ = \dfrac{31}{100}$